Antenna reeling system



Feb. 10, 1942. w, LEAR 2,272,213

ANTENNA REELING SYSTEM Filed Sept. 27, 1939 4 Sheets-Sheet l v RADIOTRANSMITTER FLEXIBLE CABLE ELECTRIC CABLE\ BELLY LINE OF AIR SHIP B TERYCABLE REMO E CONTROL UNIT I8 INVENTOR. W/Z 1/4/ 1 (64/? BY WQM ATTORNEY.

4 Sheets-Sheet 2 fNvENToR.

ATTORNEY.

Mum/v R 154/? Feb. 10, 1942. w. P. LEAR ANTENNA REELING SYSTEM FiledSept. 2'7, 1939 ml mj Nu Wm 9352: 409200 mkoimm Feb. 10, 1942. w. P.LEAR ANTENNA REELING SYSTEM 4 Sheets-Sheet 3 Filed Sept. 27, 1939ATTORNEY.

Feb. 10, 1942. w. P. LEAR ANTENNA REELING SYSTEM 4 SheBt's- -Sheet 4Filed Sept, 27, 1959 INVENTOR. W/AA/AM f1 154/1 ATTORNEY.

Patented Feb. 10, 1942 UNITED STATES iQATENT OFFICE ANTENNA REELTNGSYSTEM William P. Lear, Dayton, Ohio, assignor, by mesne assignments, toLear Avia, Inc., Piqua, Ohio Application September 27, 1939, Serial No.296,725 Claims. (Cl. 25033) This invention relates to remote controlreeling systems, and more particularly relates to novel reelingarrangements for trailing aircraft radio antennae.

A trailing wire is the most efiicient antenna for a radio transmitter ofan aircraft in flight. A one-quarter wave length antenna is the mostefficient length for such trailing antenna wire, th high potential thenbeing at its trailing end giving a marked radiation efficiency. Eachfrequency of transmission has its own optimum antenna length.

In accordance with the present invention, I provide remotely controlledmechanism for extending a trailing wire antenna in predetermined amountscorresponding to the frequency of radio transmission. The pilot needmerely set a pointer opposite the proper indication on ,a control panelto cause an exact predetermined length to be extended. Thus a maximumcome munication range is assured for a given transmitter power, andconversely, a minimum size transmitter is required for a given radiotransmission range.

The presence of an extended trailing antenna wire during landing andtake-off maneuvers is rather dangerous. 'It has heretoforebeen necessaryat such times for the pilot to watch out for and effect retraction ofany trailing wire. In accordance with my present invention I provideautomatic means controlled by the velocity of the aircraft whichprevents the extension of a trailing wire prior to take-off or until theaircraft attains a minimum predetermined velocity. The inventionfurthermore is adapted to automatically retract any extended wire whenthe aircraft falls below a predetermined minimum speed prior to landing.The pilot is this way not concerned about dangerously dangling wiresduring low flight speed or altitude.

In carrying out my present invention I employ a novel retractablefairlead for the wire antenna with two coacting sections mechanicallybiased apart in a manner to prevent snapping of the trailing wire, tokeep it taut and to prevent its rattling after reeling in. A safetyswitch is also incorporated with the retractable fairlead arranged toautomatically deenergize the control motor circuit at the proper time toprevent breakage of the antenna wire upon reeling in. I further providea novel auxiliary antenna arrangement projecting beyond the mainantenna, insuring continuous radio communication with the local airportafter the main antenna is retracted.

The remote reel and associated driving arrangement is assembled in anovel unitary construction. The unitary assembly is placed-adjacent theportion of the aircraft throu h which the wire antenna projects. It isdesigned for compactness and with a minimum bulk and weight. A novelsafety casing is incorporated with the antenna wire reel to protectadjacent .sections of the aircraft from damage should the antenna wirefor any reason snap. The casing prevents whirling about of the wire. Anovel remote control unit is electrically and mechanically interrelatedwith the reeling mechanism, and is arranged .to insure extensionandretram tion of predetermined lengths of the antenna wire inaccordance with settings made on a calibrated dial of the control panel.Switches within the control unit correlate the dial settings with theamount of wire extended, effecting a positive remote control action onthe reel motor drive.

The novel vehiclevelocity responsive switching means of mypresentinvention may be employed to initiate other functions besidethoseof antenna reeling. Thus, for example, when the speed of an aircraftfalls below a predetermined value, such as miles perhour, many of theoperations which the pilot is normally called upon to then perform maybe automatically controlled by such switch. The velocity switch is, inthe preferred embodiment, made responsive to an air pressure developedby the Pitot tube usually present and .connected with other aircraftinstruments or separately provided. The switch is electrically relatedwith relays or other means to function in the required manner. Landinggear or flap signal warnings may be actuated by.the..velocity switchwhen the speed of the aircraft requires it, reminding the pilot ofoperations necessary at the time. Predetermined automatic operation ofthe landing gear, flaps, antenna feel, or other aircraft components maybe arrangedwith such switch when the aircraft reaches, or falls below, apredetermined speed.

It is accordingly an object of my present invention to provide a novelmethod of and means for automatically performing mechanical, electrical,or other operations or functions upon an aircraft or other high-speedvehicle when its velocity falls below or rises above a predeterminedvalue. v

Another object of my present invention is to provide'a novel method ofand means for remotely controlling a reeling mechanism.

Still another object of the invention provides a novel apparatus forremotely controlling the extension and retraction of a trailing wireantenna aboard a high-speed vehicle such as an aircraft.

A further object of the invention is to provide a novel method of andmeans for automatically retracting an extended wire antenna aboard anaircraft when its velocity falls below a predetermined value.

Still a further object of the invention is to provide a novelarrangement for automatically deenergizing a wire reeling motor controlsystem when a desired amount of wire is extended or retracted.

Other objects of the present invention are to provide novel retractablefairlead constructions preventing damage to an antenna wire upon reel--ing in; means for automatically stopping the reel driving mechanism uponfull wire retraction; and auxiliary antenna means for insuring localradio communication upon full retraction of the main wire antenna. Thiscase is a continuationin-part of my copending application, Serial No.141,466, filed May 8, 1937, entitled Antenna.

These and further objects of my invention will become apparent from thefollowing description of preferred embodiments thereof taken in con v.'

nection with the drawings, in which:

Fig. 1 is an assembled view of the components of one form of the remoteantenna reeling mechanism as installed aboard an aircraft.

Fig. 2 is a diagrammatic electrical and mechanical representation ofdetails of the antenna reeling system corresponding to Fig. 1.

Fig. 3 is a horizontal cross-sectional view through the remote controlunit taken along the line 3-4 of Fig. 1.

Fig. 4 is an end view of a roller contacting arrangement for the antennawire, corresponding to the view seen along the line 44 of Fig. 1.

Fig. 5 is a plan view of the unitary antenna reeling assembly andfairlead of Fig. 1.

Fig. 6 is a cross-sectional view through the antenna reel and associateddriving arrangement as taken along the line 6-6 of Fig. 5.

Fig. 7 is a vertical cross-sectional view through the retractablefairlead and associated switching mechanism as taken along the line 'IIof Fig. 1.

Fig. 8 is an elevational view of a modified fairlead construction.

Fig. 9 is a vertical cross-sectional view through Fig. 12 is aperspective view of a safety casing for the antenna reel.

An assembly view of a physical embodiment of the remotely controlledantenna reel of my invention is illustrated in Fig. 1. The antenna wireI is wound upon a reel II of insulating material and extends through aguide-tube or fairlead I2 to a streamline fish or weight I3 attached toits end. Reel I I is mechanically connected to the electric motor I4through a reduction gear arrangement I mounted upon a unitary chassisconstruction I6. The motor I4 is electrically connected by cable I! tothe remote control box I8 situated near the pilot. Battery cable I9connects to a primary source of current on the aircraft. I prefer to usethe standard 12 volt direct current battery for operating motor I4 andthe control circuits therefor. A flexible cable 20 mechanically connectsthe remote control box It to antenna reel II and the reduction gearingI5. A positive control of, as well as an indication for the length ofantenna wire Ill extended or retracted is made possible by flexibleconnection 20.

Chassis I6 supports the antenna reel and associated structure includingmotor I4 and reduction gearing I5 as a compact unitary mechanism.Chassis I6 is drilled with mounting holes for attachment thereof to theprimary structure of the aircraft. The unit is preferably mounted withflared end section 2i projecting through tube I2, together with fish I3,extending through the fuselage of the aircraft as indicated by the bellyline 22 of the aircraft. Antenna wire In is in continuous electricalconnection with terminal post 23, connected to output terminal 24 ofradio transmitter 25 by connection lead 26. It is to be understood thatantenna It may be used for radio reception as well as for radiotransmission.

The radio transmitter 25 is located adjacent the motor-reel unit whichis located near belly line 22 of the aircraft. The radio transmitter 25is remotely controlled or operated in a manner well known in the radioart so that it may be located remote from the control region of theplane. This arrangement permits a very short and direct connection 26between the outlet of the transmitter 25 and the antenna reel I0. Thevery short connection lead 26 permits negligible radiation of theantenna signal within the aircraft structure, since the radiation occursalong the conductor connected to the high potential radio frequencyoutput of the transmitter 25. The location of the motor-reel unit nearthe point of the plane through which the antenna projects facilitatesthe reeling-in and reeling-out operations and minimizes radio frequencyenergy losses.

The important advantages of my novel variable length trailing wireantenna system reside in that the pilot may adjust the trailing wireportion to obtain optimum transmission eificiency of the radiotransmitter 25, and that the antenna reel I0 and projecting portionsthereof are directly connected to the output terminal 24 of the radiotransmitter 25 by a short connection 26 to prevent radiation lossesinternally in the aircraft. The radio transmitter is preferably remotelycontrolled from the dashboard to which it is connected by the electricalcable indicated at 25'. The remote control radio transmitter is operatedby a motor and relays, not shown.

Although I prefer to operate the antenna reel I 0 by the automaticallyoperated electrical motor system illustrated in the drawings, it is tobe understood that manual operation of the reel from the controlposition of the pilot is feasible by means of a flexible cable ortorsion shaft. Such modification requires a hand lever or wheelrotatable by the pilot from the position corresponding to that of theremote control It shown in Fig. 1 operating upon flexible shaft or cable20, which cable is directly geared to the antenna reel unit II). Amaterial advantage of the automatic over a manually operated reelingsystem is that the pilot is relieved of any winding duties which themanual antenna reel system would entail. Other features of my presentinvention, while illustrated in connection with an electrically operatedsystem, may also be derived in conjunction with a manually operatedmechanical system.

A further important feature of my invention resides in providing anautomatic safety switch 21 for preventing unreeling of the trailinganfor reeling-in and fully retracting the antenna It] at all timesexcept when the speed of the airplane is above the predetermined speed.Safety switch 21 is suitably connected to the motor-reel circuit andresponsive to an airpressure created by the motion of the aircraft inflight. I prefer to obtain the air pressure from the Pitot tube which isstandard equipment on airplanes in conjunction with instruments formeasuring various conditions of flight. The safety switch 21 can bearranged to be responsive to a pressure greater than atmospheric foractuating the safety switch relay in a manner to be hereinafterdescribed.

Safety switch 21 is connected to air pressure tube 28 which communicateswith the standard Pitot tube 29 mounted upon the wing structure 30 ofthe aircraft. Pitot tube 29 may be located at any suitable portion ofthe aircraft. It is to be understood that the differential air pressureactuating the safety switch may be generated by other i 1 to the airtube 28 when the ship attains the predetermined minimum velocity, suchas seventy miles per hour.

Remote control unit I8 contains a scale 3| calibrated in feet or lengthof antenna wire I extended from the reel II. In operation, lengthcontrol pointer 32 is manually turned to point to the number in feetcorresponding to the length it is desired to extend antenna I0. Byturning switch 33 into the out position, reel motor I4 will be energizedto rotate in the direction to unreel antenna ID. The streamline weightor fish I3 serves as a drag unit to draw antenna ID downwards and awayfrom the ship in a manner well known in the art, giving a taut antennastructure. L

Flexible cable 26 is mechanically connected to control unit E8 in amanner to be described and cooperates with the setting of controlpointer 32 for automatically stopping the operation of motor I4 when thepre-set length of antenna has been unreeled.

When switch 33 is turned to the in position, the electric motor I4 isconnected to rotate in the proper sense to reel-in the extended antennawire ID. When the antenna wire is practically reeled in, weight I3attached to the end portion thereof through the swivel joint connection35. Flexible trailing wire or tail 36 is preferably six to ten feet inlength, so as to project beneath the aircraft and not interfere withlanding or take-off operations of the airplane. Tail 36 is sufficientlylong for efficient practical communication with the landing field duringlanding and take-off. After the plane has attained its normal flightspeed, the proper length of antenna is extended abuts bell-shaped andmember 2|, and actuates switch 34 to open the motor circuit and preventfurther reeling-in. The switch 34 is the inlimit switch for preventingbreakage of the antenna wire I!) and for automatically stopping themotor at the proper instant. I provide a further motor cut-off means atthe control box unit for independently disconnecting motor I4 as afurther precaution to prevent injury to the mechanism should weight [3be broken off and unable to operate in-limit switch 34. Weight I3 isconnected to the end of antenna ID by ball-bearing swivel joint 35insuring free rotation of the weight and prevent its twisting off. Thestreamline contour of the weight I3 minimizes its aerodynamic resistancein flight.

A flexible trailing wire 36 of fixed length extends beyond the leadweight l3, and is in continuous electrical contact with antenna wire I0depending upon the communication requirements, well known in the radioart.

Pilot lamps 31 light up on remote control unit I8 when trailing antennawire I0 is extended, and serve as a warning that the antenna isextended. The pilot lamps 31 are automatically cut-off when the antennaI0 is completely retracted as will become evident hereinafter.

Fig. 2 is a schematic diagram showing preferred electrical andmechanical connections corresponding to the antenna reel mechanismillustrated in "Fig. 1. Remote control unit I8 comprises worm gear 46driven by worm M which is mechanically connected to reduction gear unitI5 by flexible cable 25. Gear 45 is rotated so as to correspond to theactual rotation of reel II and serves as a measure of the degree towhich the wire I0 of reel II is extended. The gear 40 is illustrated inits normal position, corresponding to the fully retracted position ofantenna ID as shown. In this position, an insulation nib or projection42 operates against cam switch 43 to maintain it open. A disk 44 isconnected to gear 40 by means of a frictional coupling indicated at 45.Disk 44 is mechanically secured to control pointer 32. An insulatedprojection 45 is attached to disk 44 in a predetermined position foractuating cam switch 41.

Safety switch 21 comprises a housing 48 having a flange 49 at one endfor mounting onto a suitable portion of the aircraft. A flexiblediaphragm 5B is suitably supported within housing 48 and is preferablymounted to prevent air leakage around the diaphragm. The air pressuretube communicating to Pitot tube 28, 29 connects to one side of the airchamber formed by diaphragm 50 through opening 5| in flange 49. Thepressure on the right side of diaphragm 50 of Fig. 2 depends upon thatdeveloped at Pitot tube 29 or other device for creating a pressure inaccordance with the velocity of the aircraft as hereinabove referred to.The left air chamber within housing 48 communicates to atmosphericpressure by means of an opening to the atmosphere.

Relay contacts 52, 53 and 54 are mounted within safety switch structure48 as schematically indicated. Double contact 53 is supported centrallyon diaphragm 53. Contacts 52, 53 are open during normal pressureconditions corresponding to zero, and during zero or low flight speed ofthe aircraft. However, contacts 53, 54 are in contact when the speed ofthe airplane is below the predetermined rate or is zero. When contacts53, 54 are in electrical contact, the motor circuit is energized toretract any extended portion of antenna Iii back upon reel II, andconversely, prevent any unreeling of the antenna.

The unreeling or extending operation of the antenna wire I0 can occuronly when contacts 52 and 53 are connected in response to the airpressure developed on the right hand chamber in the safety switch 2'! ascommunicated from the air pressure tube 28. It is to be understwd thatit is feasible to operate on the vacuum side of the Pitot tube, or witha different pressure device wherein air pressure is developed in therighthand chamber deflecting diaphragm 50 to the left and closingcontact 53 upon contact 52. If a vacuum pressure is used for actuatingswitch 21, it is obvious that the relative position of contacts 52 and54 will be reversed so that the deflection of the diaphragm to theright, in response to decreased pressure in the right-hand chamber willclose the contacts of the circuit corresponding to 52 and 53.

In order to extend the antenna a predetermined length, the pointer 32 isturned opposite the figure on dial 3| (Fig. 1) corresponding to thatlength. Disk 44, being mechanically coupled with pointer 32, isangularly displaced therewith the same amount, moving projection 46 awayfrom the cam switch 41 as shown in solid lines in Fig. 2. The dottedline position 46a of the projection is the cut-out position, for openingthe motor circuit at cam switch 41 when the predetermined length ofantenna III has been unreeled or extended as will be hereinafterdescribed. The displacement of projection 46 and pointer 32 shown inFig. 2 represents about onefifth of a revolution for disk 44 andcorresponds to approximately one-fifth of the antenna to be extended.If, for example, the length of the extensible antenna is one hundredfeet, such setting will correspond to about twenty feet as marked ondial 3| shown in Fig. 1. Cam switch 41 is permitted to close by thedisplacement of projection 46, and the out circuit is completed throughrelay 56 as follows:

A series circuit extends from switch 41 through connection lead 55 toout relay 56 and ground. The other side of cam switch 41 is connected toin-out switch 33 through connection lead 51 and continues from switch 33through connection lead 58 through closed safety switch contacts 52, 53back through connection lead 59 of Pitot switch cable 60 to theungrounded terminal of battery 6|. Battery 6| is preferably the standarddirect current battery of the airship, or any other suitable voltagesource for actuating motor l4 and the associated relay circuits.Summarizing, cam switch 41 is closed after pointer 32 is displaced to areeling-out position, connecting battery 6| in series with out relay 56when in-out switch 33 is connected to the out position, and when safetyswitch contacts 52, 53 are in contact under flight conditions.

When out relay 56 is energized, its armature circuits 62 and 63 areclosed and accordingly directly connect armature 64 and series fieldwinding 65 of reel-motor l4 across battery 6|. Motor i4 is illustratedas a series motor which operates on direct current from battery 6|. Thesense of rotation of motor |4 depends upon the relative connection ofseries field 65 with respect 'to armature 34 as is well known in theelectrical art. By-pass condenser 66 is preferably connected acrossarmature 64 to suppress high frequency currents which might be generatedby motor commutation. When out relay 56 is energized, reel motor I4 isaccordingly energized to rotate in the predetermined directioncorresponding to the reeling-out of antenna wire l0.

Armature 64 of motor I4 is directly coupled to reduction gearing bycoupling member indicated at 61 and drives reel at a predetermined rate.When antenna I0 is let-out or unreeled, fish or weight l3 holds the wiretaut. When weight |3is released from bell end 2| of slidable tube 10, itpermits spring 68 to draw tube 10 out and close contacts 34 of thein-limit switch.

When switch contacts 34 are closed, a circuit is completed throughconnection leads TI and 12 to the signal or pilot lamps 31 which areconnected in parallel, back through connection lead 13 and to battery6|. Switch 34 accordingly completes the pilot light circuit whichflashes an indication on remote control unit |8 that some portion of theantenna is extended. When the antenna is retracted, weight I3 abutsflared end 2| of sleeve 10 against the action of the spring 68, andopens switch 34. The circuit to indicator lights 31 is then opened andthe pilot is apprised that the antenna is fully retracted. By the termfully retracted I mean that the extensible portion of antenna I0 issubstantially fully drawn in to the position as shown in the drawings.The tall or flexible appendage 36, useful for short distancecommunication, remains extended in the preferred design of the antennareel mechanism. The opening of switch contacts 34 also opens the circuitof motor 14 if it is still in circuit connection. When weight 13 movesagainst the flared sleeve 2| the antenna wire is prevented from snappingor breaking.

Antenna I0 is unreeled by positive motivation of motor |4 when themechanism is connected to the out position, as shown in Fig. 2. Therotation of reel Il correspondingly rotates worm 4| through flexiblecable 20 and drives worm gear 40 in a counter-clockwise direction. Therotation of worm gear 40 moves disk 44 counterclockwise due to thefrictional coupling 45 therebetween. Accordingly, as antenna I0 isextended, projection 46 is rotated counter-clockwise back towards itsoriginal dotted line position 46a.

When projection 46 reaches the position 46a, cam switch 41 is opened todisconnect motor l4 and discontinue the unreeling operation. The angularmovement of gear 40 and disk 44 is preferably calibrated to correspondwith the actual length of antenna extended during the reeling operation.The effect of projection 46 is to disconnect the motor circuit afterdisk 44 has rotated an amount corresponding to the calibrateddisplacement thereof, twenty feet in the present example. Projection 42on worm gear 40 is moved to the dotted position 42a, electricallyclosing cam switch 43 to the dotted position 43a.

The reeling-in or retracting operation of the antenna I0 is accomplishedby connecting switch 33 to the in contact. Cam switch 43, being closedin dotted position 43a, causes in relay '15 to be energized since thefollowing series circuit is completed: lead 16 to relay 15, to contacts34 (which are closed when antenna I0 is extended), to ground, throughbattery 6 to cable lead 71, back through connection lead 59, acrosssafety switch contacts 52, 53, to switch 33 through lead 58, back to camswitch 43 and to the closed dotted line position 33a of the in-outswitch.

Energization of in-re1ay 15 attracts its armatures l8 and 19 to closethe circuit of motor l4 through battery 6| to cause it to rotate in theopposite direction to that when armatures 62 and 63 are closed by theout relay. Reel II is accordingly rotated to retract antenna I0 untilweight l3 abuts sleeve It at the flared end 2| and opens in-limit switchcontacts 34. The in relay 15 is then immediately deenergized, openingthe motor circuit.

During the retracting operation flexible cable 20 correspondinglyrotates worm gear 40 in a clockwise direction, bringing projection 42 toits original position, shown in solid lines, to open cam switch 43.Opening of cam switch 43 by projection 42 may not occur simultaneouslywith the opening of the in-limit switch 34. However, switch 34 is thesafety means for insuring proper opening of the reeling-in circuit sinceit is the positive indication of complete retraction of antenna I0.Projection 42 serves as a check for opening the motor circuit in timeshould Weight I3 be lost or otherwise fail to function, preventingcontinuous and high-speed reeling of the system at that time.

The frictional engagement between disk 44 and gear 43 moves projection46 from position 46a corresponding to an extended position of disk 44when pointer 32 is displaced, back to its original position 46 when theantenna is fully retracted. To again extend the antenna to the samedegree corresponding to the position of pointer 32, it is merelynecessary to reconnect switch 33 to the out position. To extend theantenna a different amount, it is merely necessary to shift pointer 32to the position opposite the length to be extended as marked on dial 3|and the apparatus will function to extend the wire the new amount. Thereeling-out operation of the antenna system of the illustratedembodiment can occur only when safety switch 21 is actuated by apredetermined pressure in the air pressure tube 28 to close contacts 52,53'. Means may be provided to short-circuit the action of switch 2?, orit may be eliminated.

Should the speed of the plane fall below the predetermined speed so thatdiaphragm 50 moves towards the right to open contacts 52, 53, anyreeling-out operation becomes ineffective through the normal control atswitch 33. Relay contacts 53, 54 are closed when the speed of the planeis sufiiciently reduced, closing the retracting or reeling-in circuitthrough leads 59 and 80, by short-circuiting in-out switch 33 to the inposition. The effect of the reduced speed of the aircraft is toautomatically throw in-relay I into circuit since cam switch 43 will benormally closed to position 430. if any of the antenna II] is extended.Energization of relay operates motor I4 to rotate reel II to retractantenna I0 until weight I 3 abuts sleeve I9 and opens inlimit switch 34.The motor circuit is then immediately disconnected from battery BI andthe antenna is safely retracted for landing operations of the plane. TheWarning lamps 31 are continuously in circuit and light up while antennaI0 is extended to any degree and in-limit switch is closed.

Fig. 3 is a cross-sectional View taken horizontally through remotecontrol unit I8 along line 3--3 of Fig. 1. The housing 8| is cast with aboss 82 for supporting worm M, and a bearing 84 for supporting controldisk 44 and worm gear 49. A back plate 83 is screwed onto housing BI andmay contain holes for mounting the unit I8 onto the aircraft structure.Worm 4! meshes with the worm gear 4|). Worm gear 40 is attached tosleeve 35 coaxial about rod 85. Sleeve 85 is closely fitted about rod 86to form a frictional engagement therewith. Dial 31 is peened onto ashoulder at the end of sleeve 85 and accordingly rotates directly withgear 49. The selective length control pointer is secured to knob 81which is manually operated in the manner already described.

Pointer 32 and knob 81 are mechanically connected to control disk 44 bymeans of central rod 85; knob 81 being peened onto the rod 86, and disk44 secured to rod 85 by set-screw 39. A spring 95 concentric with rod 85and located within a cavity in knob 81 mechanically biases disk 44against a spacer or composition washer 9| towards worm gear 40. Disk 44is accordingly frictionally engaged with worm gear 40 and is rotatedtherewith. The positive engagement of gear 40 with worm gear 4| permitsdisk 44 and knob 81 to be manually displaced independently of the wormgear 40 and to perform the selective length control functionshereinabove described in connection with diagrammatic Fig. 2.

Fig. 4 is an end view of the continuous antenna contact means as viewedfrom the line 4-4 in Fig. 1. Guide-tube I2 is shown supported oninsulation block I 94 by strap 93. Block I04 is attached to the commonchassis I6. The edges of chassis I3 are curled over to stiffen andstrengthen the chassis. Antenna wire I0 is in continuous electrical andfrictional contact with the tubular rollers I I9 spaced by a distanceequal to the diameter of the wire I0. Rollers H0 are supported bymetallic brackets III and H2 and are electrically interconnectedtherewith. A terminal post 23 is connected to the top bracket I I2. Thewire 25 connecting to radio transmitter 25, as shown in Fig. 1, isaccordingly conductively connected to the antenna wire II) as will nowbe evident. Continuous electrical contact is maintained for the variablelength of the extended antenna. There is no danger of short-circuitingantenna ID to ground since should it be displaced from thecentralposition it could only touch upon insulation guide-tube 'I2. By leadingantenna wire II] at an angle to the central position of the wire in tubeI2, in a manner illustrated in Fig. 5, increased frictional contactoccurs at one of the rollers I I0.

Fig. 5 is a plan view of the motor-reel assembly as a unitary structurewith chassis I6. Chassis I6 is preferably of metallic material andcontains mounting brackets 92 and 93 for securing the fairlead or sleeveI2 in position. Movable or retractible sleeve I0 is slidable withinsleeve I2 and contains flared end 2I. Sleeves I0 and I2 are made ofinsulation material such as Bakelite or composition to preventshort-circuiting of antenna wire ID to ground through chassis I6. Flaredend 2| is preferably of metallic construction, such as steel, to resistshock and wear resulting from impacts by the weight I3. Reel II isrotatably supported on rod 94 adjacent the right end of the sleevestructure I2. Motor I4 is secured to chassis I6 at the extreme rightend, cooperating with the reduction gear structure (not seen in Fig. 5).Remotely controlled relays 56 and I5 are enclosed in housing 39.

The preferred physical cooperation between reel II and reduction gearingI5 is illustrated in cross-sectional View Fig. 6, taken along the lineS6 of Fig. 5. The shaft of motor I4 is coupled to worm 95 withinreduction gearing unit I5. A worm gear 96 meshes with worm 95 and iskeyed to shaft 94 secured to reel structure II. Flexible cable 2!] ,ismechanically coupled to shaft 94 by female coupling member 91 containinga socket cooperating with projection 98 of shaft 94. Flexible cable 29and its connecting head 91 is maintained in position by sleeve 99 setinto extension I of reduction gearing I 5. Antenna reel II comprisesparallel disks IIII, I02 of insulation material suitably spaced tocontain antenna wire It therebetween. The antenna is insulated from themetallic structure of the motor drive as well as the supportingstructure.

Fig. 7 is a cross-sectional view illustrating one embodiment of thein-limit switch and associated actuation arrangement as taken along theline 1-1 of Fig. 5. Outer tubular sleeve I2 is fixedly supported uponchassis I6 by straps 92, 93 and insulation blocks I03, I04. Movablesleeve 10 is slidably mounted within sleeve I2. Flared metallic member2| is secured to the outer end of slidable tube 10. A block I05 isattached to a portion of slidable tube 10 for actuating extended arm I06of in-limit switch 34.

To facilitate mounting of block I05 n tube 10, I provide a slot I I4 intube 10 located directly above the position of block I05, and a furthercorresponding slot H5 in outer tube I2. When retractable tube is in theextended position corresponding to that shown in Fig. 5, both slots H4and H5 are lined-up and permit the insertion of a screw driver or othersuitable tool for mounting block I 05. Simple holes may be substitutedfor the slots H4, H5. Outer slot II5 on tube I2 is covered over by aplate II6, such as a name plate, to prevent foreign matter from enteringthe assembly.

Block I05 accordingly is slidable with tube 10 and projects through aslot I06 on the bottom portion of the fixed sleeve I2. Spring 68mechanically biases block I05 towards the left and with it slidable tube10 as well. The normal position of tube 10 is the extended one as shownin Fig. 5, holding switch block I05 against the left end of the slotI06, away from arm I06 of switch 34.

When antenna I0 is fully retracted, weight I3 is drawn against the openend of the end member 2|, forcing tube 10 inwards against spring 66 andoperating block I05 to the position illustrated in Fig. '7. Blade I06 ispressed downwards, opening the contacts of in-limit switch 34.Conversely. when antenna I0 is extended, spring 68 moves block I05 awayfrom switch I06, effecting a closure of the contacts of switch 34. Pilotlights 31 are then lit up, and the reeling operation disclosed inconnection with Figs. 1 and 2 is permitted to take place. Antenna I0 isin continuous contact with rollers I I0 connecting with the radiotransmitter 25 by the short connection lead 26 as hereinabove describedin connection with Fig. 1.

An important advantage of the spring biased retractable tube 10 is thatantenna wire I0 is kept taut when the antenna is completely retractedand the motor is disconnected when holding weight I3 firmly againstflared end 2|. In practice, tube 10 is made retractable to the extent ofseveral inches. Reel I I is prevented from unwinding when motor I 4 isnot operating, due to the mechanical interlocking of worm gear 96 withworm 95, as shown in Fig. 6. With weight I3 against flared end 2 I, tube10 is forced inwards against spring 60, maintaining antenna I0 tautafter the motor circuit is disconnected. The practical advantagesresulting are that weight I3 is prevented from vibrating or chatteringagainst nearby objects when the antenna is retracted, and a firmelectrical connection between the tall 36 and the radio transmitterefi'ected. Antenna tail 36 remains extended for local radiocommunication.

The safety switch 21 has been illustrated as electrically connected inthe motor control circuit to prevent the extension of the antenna I0before the plane has reached a predetermined speed and to automaticallyretract the antenna should any of it be extended when the aircraft isflying below the predetermined speed. My invention,

however, may be practiced without the use of a. safety switch by merelyconnecting the remote control unit directly to the motor circuit relaysas will be evident to those skilled in the art.

A modified form of the fairlead is illustrated in Figs. 8 to 11. Fig. 8is an end view of the fairlead, in extended position. Two concentrictubes I20 and I2I coact in a manner similar to tubes I2 and 10 of thepreviously described embodiment. Outer tube I20 is fixedly mounted onthe chassis or another desired base by metal straps I22 and bolts I23.The streamlined weight or fish I25 is coupled by swivel joint I26 toloop end I21 of reelable antenna wire I30. Antenna wire I30 extendswithin concentric tubes I20 and I'll.

Projecting antenna portion I28 from fish I25 corresponds to the highfrequency communication antenna portion 36 of the previous embodiment.The in-limit switch I3I corresponds to in-limit switch 34 of theprevious embodiment. In the present form it comprises a toggle switch.Arm I32 of toggle switch I3I is in a Y-form having projections I33 andI34 extending through tube I20 to coact with slidable tube IZI.Electrical connections I35 for the motor control circuits are made tothe terminals of in-limit switch I3I, corresponding to the connectionswith switch 34 shown in Fig. 2.

Fig. 9 is a vertical cross-sectional view through the modified fairleadconstruction, with antenna wire I30 and fish I25 in the fully retractedposition. Fish I25 abuts against a flared or tapered opening of metallicend member I36 affixed to the end of slidable composition tube I2I. Aspring I31 is contained within composition tube I 20, positioned betweenthe right end of tube I2I and metallic insert I38 on the correspondingend of tube I20. Spring I31 is a compression spring arranged tocontinually mechanically bias tube I2I outwardly from tube I20.

The relatively short antenna section I28 projects centrally throughstreamlined weight I25 and is conductively related with swivelconnection I26 at the end of the weight. Reelable antenna wire I30 ismechanically connected with swivel joint I26 through looped end I21 ofwire I30. When main antenna wire I 30 is fully reeled-1n to the positionshown in Fig. 9, streamlined weight I25 abuts end member I36 forcingslidable tube I2I inwardly to tube I20 and rendering wire I30 taut. Afirm mechanical and therefore electrical interconnection is thus madethrough swivel joint I26 between looped end I21 of antenna I30 andantenna section I28 when antenna I30 is fully reeled-in.

The reelable antenna wire I30 and the radio transmitter (or receiver)are in continuous electrical connection, such as by a sliding or rollercontact means (similar to roller connections IIO of Fig. 4) or othersuitable means. The tail antenna I28 is used for local radiocommunication when the main antenna wire I30 is fully reeledin. The tautrelation between swivel I26 and the looped end I21 insures an eilicientelectrical connection of tail antenna I28 with the radio transmitter (orreceiver) in the aircraft. Radio communication is thus carried onwithout danger of a long projecting antenna wire during landing ortake-off maneuvers, as set forth hereinabove.

Slidable tube I2I is held again rotation or angular displacement withrespect to fixed tube I20 by bolt-head I40 coacting with longitudinalslot or groove MI in tube I2I. Enlarged cross-sectional Fig. 10, takenalong the line I0I0 of Fig.

9, more clearly illustrates the coactionv of head I40 of bolt I42 withgroove I4I. Bolts I42 and I43 secure the extended end of bracket I45with fixed sleeve I20. Bracket I45 holds toggle switch I3I in fixedposition on sleeve I20. The. opposite end of bracket I45 is secured totube I20: by bolt I46 as shown in Fig. 9.

Longitudinal groove I4I is aligned with arms I33, I34 of toggle switchI3I extending therewithin. Toggle switch I3I is actuated in accordancewith the in and out positions of tube I2I with respect to tube I20. incircular groove I49 of tube IZI, coacts with arms I33, I34 of in-limittoggle switch I3I. By aligning extending arms I33, I34 of switch I3Iwithin groove I4I, abutting member I41 need not project beyond th outersurface of slidable tube I2I. The surface of member I41 is flush withthe surface of tube IZI, and does not interfere with the sliding of thetube. Fig. 11 is an enlarged cross-sectional view taken along the lineII-II of Fig. 9 through the ring I41 and coacting elements. Ring I41 isshown semi-circular and secured to tube I2-I by pin I48.

When tube I2I is moved to the retracted position shown in Fig. 9, onreeling-in of wire I30, member I41 abuts extending arm I34 of toggleswitch I3I, moving it to open switch I3I and deenergizing the motorcontrol circuit in the manner previously described to prevent furtherreeling of wire I30. This serves as a safety in-limit feature. When thewire I30 is reeled-out, it is no longer taut and compression spring I31extends movable sleeve IZI from sleeve I20. as shown. in Fig. 8. As tubeI20 is moved outwardly by spring I31, member I41 is moved againstextending toggle switch arm I33 to electrically close toggle.

switch I3I. This action reconnects the in-limit circuit through switchI3I, corresponding to the. safety in-limit circuit including switch 34through in-relay 15 shown in Fig. 2.

In Fig. 12, I illustrate a fixed enclosure I50 for the rotatable antennareel II to prevent damage to. the aircraft should th antenna wire I30for any reason break or snap. Heretofore, if the reelable antenna broke,the dangling wire end extended beyond the reel while it rotated, causingdamage to adjacent aircraft portions. By providing safety casing I50coacting with but not interfering with the operations of reel II thisdanger is eliminated. The diameter of casing I50 is slightly larger thanthat of reel I I, providing an annular space I55 thcrebetween to'permitfree rotation of the reel. Reel II is driven through shaft 04 by themotor controls as previously explained in connection with Figs. 5. and6.

The safety casing I50 is fixedly mounted to the chassis or othersuitable base by bracket II. The ends of bracket I5! are secured tocircular casing 50 by rivets I52, or other suitable means. Holes I53 inthe bracket provide for its connection with a base or chassis. A wideopening I54 in the side of safety casing I50 permits antenna wire I30 tobe reeled by the encased reel I I. Casing I50 may be tubular and ofequal width with reel II. A rear wall portion is preferably added tocasing I50, not shown in the perspective Fig, 12. The reel II is readilyassembled with safety casing I50.

Although I have described preferred arrangements for carrying out mypresent invention, it is to be understood that modifications thereof arefeasible without departing from the broader spirit and scope thereof,and accordingly I do A ring I41, secured I not intend to be limited,except as set forth in the following, claims.

What. I claim is:

1. An antenna system for an aircraft comprising a reel containing anantenna wire; a motor for operating said reel; retracting meansincluding circuit connections to said motor for energizing said motor toreel-in extended antenna wire; and means for limiting the reeling-in ofsaid wire comprising a protuberance secured to the wire, an insulationtube through which said wire passes having a switch operating. portion,a switch circuitally connected with said retracting means and operableby said tube portion, whereby said tube is abutted by said protuberanceand displaced to operate said switch to deenergize said motor.

2., An antenna system for an aircraft comprising a reel containinganantenna wire; a motor for operating said reel; retracting meansincluding circuit connections to said motor for energizing said motor toreel-in extended antenna wire; and means for limiting the reeling-in ofsaid wire comprising a weight secured to the wire, an insulaticn tubeconcentric about the wire, a spring normally biasing said tube in thedirection opposite the retracting direction, a switch circuitallyconnected withsaid retracting means and mechanically operable by saidtube, whereby said biased tube is abutted by said weight and displacedto operate said switch to deenergize said motor and stop the wirretraction, and to press said Weight to hold the wire end taut whileretracted.

3. Anantenna system for an aircraft comprising a reel containing anantenna wire; a motor for operating said reel; retracting meansincluding circuit connections to said motor for energizing said motor toreel-in extended antenna wire; and means for limiting the reeling-in ofsaid wire comprising an element secured to the wire, a slidable tubehaving a flared end through which said wire passes, a switch circuitallyconnected with said retracting means and mechanically operable by saidtube, a spring for biasing said tube towards the extended position tooperate said switch in a predetermined relation, whereby said biasedtube is abutted by said element and displaced to operate said switch todeenergize said motor.

4. An antenna system for an aircraft comprising a reel containing anantenna wire; a motor for'operating saidreel; retracting means including circuit connections to said motor for energizing said motor toreel-in extended antenna wire; and means for limiting the reeling-in ofsaid wir comprising a protuberance secured to the wire, a movablemember, a switch circuitally connected with said retracting means andhaving a Y-arm mechanically operable by said member, a spring forbiasing said member towards the extended position to operate said switchin a predetermined relation, whereby said biased member is abutted' bysaid protuberance and displaced to operate said switch to deenergizesaid motor.

5. An antenna system for an aircraft comprising a reel containing anantenna wire; a motor for operating said reel; means including circuitconnections to'said motor for extending a variable length of said wireand for stopping said motor When a, predetermined length of said wire isextended; retracting means including circuit connections to, said motorfor energizing said motor to reel-in extended antenna wire; and

means for limiting the reeling-in of said wire comprising a protuberancesecured to the wire, a member, a switch circuitally connected with saidretracting means and operable by said member, whereby said member isabutted by said protuberance and displaced to operate said switch todeenergize said motor and stop the wire retraction.

6. An antenna system for an aircraft comprising a reel containing anantenna wire; a motor for operating said reel; means including circuitconnections to said motor for extending a variable length of said wireand for stopping said motor when a predetermined length of said wire isextended; retracting means including circuit connections to said motorfor energizing said motor to reel-in extended antenna wire; and meansfor limiting the reeling-in of said wire comprising a weight secured tothe wire, a slidable tube having a flared end through which said wirepasses, a switch circuitally connected with said retracting means andmechanically operable by said tube, a spring for biasing said tubetowards the extended position to normally maintain said switch closed,whereby said biased tube is abutted by said weight and displaced to opensaid switch to deenergize said motor.

7. An antenna system for an aircraft comprising a reel containing anantenna wire; a motor for operating said reel; means including circuitconnections to said motor for extending a variable length of said wireand for stopping said motor when a predetermined length of said wire isextended; retracting means including circuit connections to said motorfor energizing said motor to reel-in extended antenna wire; and means[or limiting the reeling-in of said wire comprising an element securedto the wire, a spring biased tube through which said wire passes, aswitch circuitally connected with said retracting means and having aY-arm mechanically operably by said tube, whereby said biased tubenormally operates said switch into circuit closing position and isabutted by said element and displaced to operate said switch todeenergize said motor and stop the wire retraction.

8. The combination with a wire reeling system of mechanism for guidingsaid wire comprising a first tube through which said wire is moved, asecond tube slidable with said first tube and having an end portionprojecting beyond said first tube in the wire extending direction forabutting a protuberance on said wire when said wire is fully retracted;and a spring arranged to mechanically bias apart said first and secondtubes whereby impact of said protuberance on said projecting tube end iscushioned and said wire is held taut in the retracted position.

9. Guiding mechanism for an extensible wire comprising a first tubethrough which the wire is moved, a second tube slidable with respect tosaid first tube and having an end portion projecting beyond said firsttube arranged for abutting a protuberance on said wire, an electricalswitch mounted on said mechanism, and a member secured on said secondtube for operating said switch to a predetermined Position when saidsecond tube is moved with respect to said first tube as saidprotuberance abuts the projecting end portion of said second tube.

10. A fairlead for an extensible antenna wire comprising a first tubethrough which the wire is moved, a second tube slidable within saidfirst tube and having a flared end portion projecting beyond said firsttube arranged for abutting a protuberance on said wire, an electricalswitch mounted on said first tube, a member secured on said second tubefor operating said switch in a predetermined manner when said secondtube is moved with respect to said first tube as the protuberance abutsthe projecting end portion of said second tube, and spring means fornormally biasing said second tube in the Wire extending direction.

11. Guiding mechanism for an extensible wire antenna comprising a firsttube through which the wire is moved, a second tube slidable withrespect to said first tube and having an end portion projecting beyondsaid first tube arranged for abutting a protuberance on said wire, anelectric switch on said mechanism; a member secured on said second tubefor operating said switching mechanism to a predetermined position whensaid second tube is moved with respect to said first tube as theprotuberance abuts said projecting end portion, and metallic rollermeans secured to said first tube arranged in a continuously contactingrelation with said extensible wire antenna.

12. Guiding mechanism for an extensible wire antenna comprising a firsttube through which the wire is moved, a second tube slidable withrespect to said first tube and having an end portion projecting beyondsaid first tube arranged for abutting a protuberance on said wire,atoggle switch on said mechanism having a Y-arm extending into coactionwith said second tube, and a member secured on said second tube foroperating said Y-arm to a predetermined position when said second tubeis moved with respect to said first tube as the protuberance abuts saidprojecting end portion.

said Y-arm to a predetermined position when said second tube is movedwith respect to said first tube as the protuberance abuts saidprojecting end portion.

14. A fairlead for an extensible wire antenna comprising a first tubethrough which the wire is moved, a second tube longitudinally slidablewith respect to said first tube and having an end portion projectingbeyond said first tube arranged for abutting a protuberance on saidwire, "a switch mounted on said first tube and having an arm extendingthrough said first tube into coaction with a longitudinal groove on saidsecond tube, and a member secured on said second tube across a part ofsaid groove for operating said arm to a predetermined position when saidsecond tube is moved with respect to said first tube as the protuberanceabuts said projecting end portion.

15. A fairlead for an extensible wire antenna comprising a first tubethrough which the wire is moved, a second tube longitudinally slidablewith respect to said first tube and having an end portion projectingbeyond said first tube arranged for abutting a protuberance on saidwire, a toggle switch mounted on said first tube and having a Y-armextending through a slot in said first tube into a longitudinal grooveon said second tube, and a member secured on said second tube across apart of said groove for operating said Y-arm to a predetermined positionwhen said second tube is moved with respect to said first tube as theprotuberance abuts said projecting end portion.

16. A unitary antenna reeling system comprising a reel containing anantenna wire; a motor for driving said reel in either direction; aretractable fairlead having two concentric tubes mechanically biasedapart for guiding said wire centrally therethrough; a chassis formounting said motor, reel and. fairlead in mechanically cooperativerelationship; and a protuberance connected at the outside end of saidwire arranged to abut the outer end of said fairlead and compress saidtubes together for maintaining said wire taut when fully retracted andprevent rattling thereof.

17. A unitary antenna reeling system comprising a reel containing anantenna wire; a motor for driving said reel in either direction; aretractable fairlead having two concentric tubes mechanically biasedapart for guiding said wire centrally therethrough, one of said tubesnormally projecting beyond the other in the wire extending direction; achassis for mounting said motor, reel and fairlead in mechanicallycooperative relationship; a protuberance connected at the outside end ofsaid wire arranged to abut said projecting tube end of said fairlead andcompress said tubes together for maintaining said Wire taut when fullyretracted and prevent rattling thereof; and a casing secured with saidchassis and extending directly over the open annular portion of saidreel to enclose said contained wire and protect adjacent structures fromsaid wire.

18. An antenna system for an aircraft comprising a reel containing amain antenna wire; mechanism for operating said reel to extend andretract said main wire with respect to the aircraft; a protuberance onthe end of said main wire; means for abutting said protuberance whensaid wire is substantially fully retracted, arranged for stopping theretracting operation of said reel; and a relatively short auxiliaryantenna wire electrically related with said main wire end and extendingfrom said protuberance outside of said aircraft, whereby said auxiliaryantenna wire permits efiicient short range radio communication when saidmain antenna is retracted, preventing physical interference with theaircraft during landing and take-off maneuvers.

19. An antenna system for an aircraft comprising a reel containing amain antenna wire; mechanism for operating said reel to extend andretract said main wire with respect to the aircraft; a protuberancemechanically linked to the end of said main wire; a swivel jointconnecting said protuberance with said main wire end; means for abuttingsaid protuberance when said wire is substantially fully retracted,arranged for stopping the retracting operation of said reel; and arelatively short auxiliary antenna wire electrically related with saidmain wire end across said swivel joint and extending outside of saidaircraft, whereby said auxiliary antenna wire permits efiicient shortrange radio communication when said main antenna is retracted,preventing physical interference with the aircraft during landing andtake-oil maneuvers.

20. An antenna system for an aircraft comprising a reel containing amain antenna wire; mechanism for operating said reel to extend andretract said main wire with respect to the aircraft; a protuberance onthe end of said main wire; a swivel joint connecting said protuberancewith said main wire end; means for abutting said protuberance when saidwire is substantially fully retracted, arranged for stopping theretracting operation of said reel; and a relatively short auxiliaryantenna wire extending through said protuberance, electrically relatedwith said main wire end across said swivel joint and extending outsideof said aircraft; and means for maintaining said main antenna wire tautwith respect to said protuberance, across said swivel joint, when saidmain antenna is retracted; whereby said auxiliary antenna wire permitsefficient short range radio communication when said main antenna isretracted, preventing physical interference with the aircraft duringlanding and takeoff maneuvers.

WILLIAM P. LEAR.

